Electrophotography, which is a method for visualizing image information by forming an electrostatic latent image, is currently employed in various fields. The term “electrostatographic” is generally used interchangeably with the term “electrophotographic.” In general, electrophotography comprises the formation of an electrostatic latent image on a photoreceptor, followed by development of the image with a developer containing a toner, and subsequent transfer of the image onto a transfer material such as paper or a sheet, and fixing the image on the transfer material by utilizing heat, a solvent, pressure and/or the like to obtain a permanent image.
In electrostatographic reproducing apparatuses, including digital, image on image, and contact electrostatic printing apparatuses, a light image of an original to be copied is typically recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles and pigment particles, or toner. Electrophotographic imaging members may include photosensitive members (photoreceptors) which are commonly utilized in electrophotographic (xerographic) processes, in either a flexible belt or a rigid drum configuration. Other members may include flexible intermediate transfer belts that are seamless or seamed, and usually formed by cutting a rectangular sheet from a web, overlapping opposite ends, and welding the overlapped ends together to form a welded seam. These electrophotographic imaging members comprise a photoconductive layer comprising a single layer or composite layers.
Conventional toner compositions suffer from issues such as lack of robustness, which is related to charge distribution and selective development. The present inventors have found that making the toner particles more spherical helps make the surface properties of the particles more uniform and hence facilitate a narrower charge distribution. This approach has been successful in stabilizing the density of the toner. The data obtained shows density dropping off over time (print count) with the lower circularity toner (for example, 0.975), as measured with a Sysmex 3000 shape analyzer. However, the more spherical toner particles (for example, 0.988) show much more stable development over time. However, robust machine components are required to clean the spherical particles at a high efficiency. Blade cleaning systems require a good balance between sufficient lubricity to prevent blade damage and sufficient normal force to prevent toner particles from getting past the blade nip. Prior methods to combat this issue involved impregnating the outer layer of photoreceptors with silicone oil. However, such methods proved cost prohibitive.
Thus, there is a desire to improve the characteristics and performance of toner compositions to address the above problems. The present embodiments are directed to toner compositions comprising silicone oil that provide improved cleanability and allow the use of spherical particles to achieve the desired density stability.